Public/Get-Years.ps1

function Get-Years {
    [CmdletBinding(SupportsShouldProcess)]
    Param (
    [Parameter(Mandatory,ValueFromPipeline)]
    [object]$YearsObject
    )

    process {
    $Years = $YearsObject.PSObject.Properties.Name | ? { $_ -match '^\d{4}$' }
    foreach ($Year in $Years) { $YearsObject.$Year }
    }
}