This page lists DVOA (Defense-adjusted Value Over Average) for total offense as well as rushing and passing offense separated. The DVOA system is explained here. DVOA stats are adjusted to an average percentage of fumbles recovered by the offense. Quarterback scrambles are counted as passing plays rather than rushing plays. Offenses are adjusted for playing indoors.
Please note that the combination of pass offense and run offense will appear to be higher than total offensive DVOA. This is because offensive DVOA also accounts for false starts and delay of game penalties, which are all negative plays but are not considered as either passes or runs.
Regular season only.
Note for 1987: strikebreaker games (Weeks 4-6) are not included.