I've worked out that the 2006/07 Ashes series created a record daily average attendance for an Australian Test summer.
This beat a 70 year old record set in the 1936/37 Ashes series.
2006/07
1st Brisbane 39288 39315 38719 37056 10369 164747
2nd Adelaide 31458 30321 30075 24552 20355 136761
3rd Perth 24175 24268 22006 20703 12288 103440
4th Melbourne 89155 75770 79426 244351
5th Sydney 46070 45572 41533 30862 164037
Total: 813,316
Days: 22
Avg: 36,969
1936/37
1st Brisbane 14303 30598 12600 7917 7400 72818
2nd Sydney 35107 43326 24894 23620 126947
3rd Melbourne 79630 65235 87798 64826 45528 7517 350534
4th Adelaide 35643 33526 28975 38334 21982 12675 171135
5th Melbourne 52342 77181 63340 31253 12000 236116
Total: 957,550
Days: 26
Avg: 36,829