Straight from my W-2s:
1999: 26K (hired mid-way through year from a higher-paying job)
2000: 24K
2001: 26K
2002: 37K (transitioned to RJ FO mid-year)
2003: 60K (upgraded mid-year)
2004: 69K
2005: 79K

It's all about work rules as mentioned above. You can't just do min. gaurantee X payrate X 12 months. There's training pay, holiday pay, user pay (sick), vacation pay, bonuses, and overtime (jr. man), and extra flying voluntarily picked up.