So the 20% of the games he didn;t bowl in are because Australia only used 4 bowlers then?
Pull the other one.
Of the 158 innings he fielded in, he bowled 5 + overs in 109 of them. He averaged over 6 overs per innings. That number as an average is skewed because we regularly bowled teams out and occasionally played someone like Hopes or Harvey as 5th bowler or we selected 3 quicks plus 2 spinners. Or it suited Clarke's/Lehmann's bowling.
FWIW, here's a list of the matches he didn't bowl in:
ODI 1485: Aust bowled SL out in 37 overs (not required)
ODI 1563: Aust did not bowl (wash out)
ODI 1565: McG, Warne, Lee, Lee bowled out NZ in 30 overs (not required to bowl)
ODI 1677: Lee, Fleming, Harvey, Warne bowl out WI in 35 overs (not required to bowl)
ODI 1938: Clarke bowls 7 overs
ODI 1940 and 41: Aust play 2 spinners (and three quicks)
ODI 1970: Aust bowl out Namibia in 14 overs
ODI 1990: Lehmann bowls 6 overs and Harvey in the team
ODI 1991 : Aust bowl SL out in 38 overs
ODI 2016: Hauritz and Hogg play along with 3 quicks
ODI 2019: Harvey is selected as 5th bowler
ODI 2053: Aust bowl NZ out in 33 overs
ODI 2159: Washed out
ODI 2172: Aust bowl USA out in 24 overs
ODI 2209 : Lehmann bowls 7
ODI 2232: Hopes is selected as 5th bowler
ODI 2256: Eng only face 6 overs before wash out
ODI 2284: ICC World XI bowled out in 27 overs
ODI 2366: Cullen and Hogg selected along with 3 quicks
ODI 2367: Ditto
ODI 2473: Clarke and White share 10 overs
ODI 2577: NZ bowled out in 25 overs
ODI 2580: Watson selected as 5th bowler
ODI 2621: Washed out
ODI 2623: Clarke bowls 9 overs
ODI 2625 - end of Symonds career (approx 12 matched where Symonds doesn't bowl): Hopes selected as 5th bowler and Symonds used as a batsman only.
You're the one that's pulling something.