How to Sort TotalItemSize Property of Get-MailboxStatistics

Hi I have this querry, but it seems that powershell only sorts the items by its number value. How can I sort TotalItemSize by its bytes

Get-Mailbox -Server server01.domain.com -IgnoreDefaultScope | Get-MailboxStatistics | Sort-Object TotalItemSize | FT DisplayName, TotalItemSize

User0                                            2.927 GB (3,142,540,900 bytes)
User1                                     2.954 GB (3,171,835,975 bytes)
User2                                              208.3 MB (218,466,864 bytes)
User3                                            209.1 MB (219,220,247 bytes)
User4                                              227.2 MB (238,197,431 bytes)
User5                                                230.4 MB (241,579,414 bytes)
User6                                            268.9 MB (281,926,061 bytes)
User7                                             27.72 MB (29,069,644 bytes)
User8                                             270.3 MB (283,465,688 bytes)
User9                                                    29.03 MB (30,444,448 bytes)
User10                                         295.6 MB (309,909,793 bytes)
User11                                                     3.003 GB (3,224,569,519 bytes)
User12                                           3.017 GB (3,238,978,160 bytes)

How can I do this in powershell?