How do i convert my values in an array/object to measure them?

i am new to stackoverflow and i'm not really a powershell crack. Maybe you can help me with my problem. For monitoring reasons i want to get a ssh result from "vmstat 1 10" on an Linux-Server. I need to get the Avarage Values of the 10 Values i have. A Usual "vmstat 1 10" result looks like this:

procs -----------memory---------- ---swap-- -----io---- -system-- -----cpu------
 r  b   swpd   free   buff  cache   si   so    bi    bo   in   cs us sy id wa st
 1  0  42352 599980 315860 2488096    0    0  2606   794    5    2  3  0 94  2  0
 0  0  42352 600044 315860 2488096    0    0    64    84 1107 2107  0  1 99  1  0
 0  0  42352 596820 315860 2488096    0    0   280     4 1218 2179  7  1 91  2  0
 0  0  42352 589240 315860 2488096    0    0    32     7 1322 2366  1  1 95  3  0
 0  0  42352 588620 315860 2488096    0    0   144    37 1161 2181  1  0 96  3  0
 0  0  42352 588620 315860 2488096    0    0     0    24 1074 2075  0  0 100  0  0
 0  0  42352 588620 315860 2488096    0    0     0     0 1081 2081  0  1 100  0  0
 0  0  42352 588628 315860 2488096    0    0   128    32 1133 2091  1  0 96  3  0
 0  0  42352 588652 315860 2488100    0    0     0     0 1077 2058  0  0 100  0  0
 0  0  42352 588528 315860 2488100    0    0     0     5 1137 2147  0  0 99  0  0

So to get the AVG of the Values like swpd, free, buff, etc. my plan was to get the whole values in an Object an then make something like $tab.swpd | Measure-Object -avg but i get an error.

Here is my Script to get the values in the Object. (I know that this is not very nice - sorry for that. I'm still learning...):

$runs = 10
#Get the Values via plink (putty)
$vmstat = .\plink.exe -ssh USER@SERVER -batch -pw "PASSWORD-YES-I-KNOW-THIS-IS-BAD" vmstat 1 $runs
$vmstat
##########################
#Get the Values in somthing like a csv
$vmstat = $vmstat.replace(" ", ";")
#replace alle double ";;" with single ";"
while ($vmstat -match ";;"){
    $vmstat = $vmstat.replace(";;", ";")
    }

#Delete ";" at the beginning (and at the end. Just to be sure. normally there arent ";" 's)
$vmstat = $vmstat.Trim(";")
#Save Columnames
$tabhead = $vmstat[1].split(";")
#Delete first and second row
$vmstat = $vmstat[2..($runs+1)]

##########################
#Split Values and Store it in an two-dimensional array
$values = New-Object system.Array[][] $tabhead.Length, $runs

for ($i=0;$i -lt ($vmstat.Length); $i++){
    $tmp = $vmstat[$i].split(";")

    for ($j=0;$j -lt ($tmp.Length); $j++){
        $values[$j][$i] = $tmp[$j]
        }
}

##########################
# Make an Object for Measurement!
$tab = New-Object System.Object

for ($i=0;$i -lt $tabhead.Length; $i++){
    $tab | Add-Member -type NoteProperty -name $tabhead[$i] -Value $values[$i]
}

so after that all my Values are like i want in the Array or in the Object. I am Able to do select Values i want to see:

PS C:\> $tab

r     : {1, 0, 0, 0...}
b     : {0, 0, 0, 0...}
swpd  : {42352, 42352, 42352, 42352...}
free  : {599980, 600044, 596820, 589240...}
buff  : {315860, 315860, 315860, 315860...}
cache : {2488096, 2488096, 2488096, 2488096...}
si    : {0, 0, 0, 0...}
so    : {0, 0, 0, 0...}
bi    : {2606, 64, 280, 32...}
bo    : {794, 84, 4, 7...}
in    : {5, 1107, 1218, 1322...}
cs    : {2, 2107, 2179, 2366...}
us    : {3, 0, 7, 1...}
sy    : {0, 1, 1, 1...}
id    : {94, 99, 91, 95...}
wa    : {2, 1, 2, 3...}
st    : {0, 0, 0, 0...}

PS C:\> $tab.in
5
1107
1218
1322
1161
1074
1081
1133
1077
1137

But when i try somthing like: $tab.swpd | Measure-Object -Average i get the following error:

Measure-Object : Das Eingabeobjekt "System.Object[]" ist nicht numerisch.
In Zeile:1 Zeichen:13
+ $tab.swpd | Measure-Object -Average
+             ~~~~~~~~~~~~~~~~~~~~~~~
    + CategoryInfo          : InvalidType: (System.Object[]:Object[]) [Measure-Object], PSInvalidOperationException
    + FullyQualifiedErrorId : NonNumericInputObject,Microsoft.PowerShell.Commands.MeasureObjectCommand

i think i even would not need the Object, i think it must also be posible to do something like $values[0] | Measure-Object -Average but there is the same error. I know the Problem is that the values arent int values. But i dont know how to convert them so i can make my measurements.