Found a new source.
No. 1: U.S.
Total millionaire households: 4,585,000
Change in 2005-06: +10%
Growth rank: 13 (of 15)
Total population: 301,139,947
Total $100 million+ households: 2,300 (rank: 1)
Change in 2005-06: +7%
Growth rank: 14
No. 2: Japan
Total millionaire households: 830,000
Change in 2005-06: +7%
Growth rank: 15
Total population: 127,433,494
Total $100 million+ households: 1,300 (rank: 2)
Change in 2005-06: +6%
Growth rank: 15
No. 3: Britain
Total millionaire households: 610,000
Change in 2005-06: +30.5%
Growth rank: 3
Total population: 60,776,238
Total $100 million+ households: 810 (rank: 3)
Change in 2005-06: +25%
Growth rank: 4
No. 4: Germany
Total millionaire households: 350,000
Change in 2005-06: +21%
Growth rank: 10
Total population: 82,400,996
Total $100 million+ households: 620 (rank: 4)
Change in 2005-06: +18%
Growth rank: 10
No. 5: China
Total millionaire households: 310,000
Change in 2005-06: +39%
Growth rank: 1
Total population: 1,321,851,888
Total $100 million+ households: 180 (rank: 13)
Change in 2005-06: +74%
Growth rank: 1
No. 6: Italy
Total millionaire households: 270,000
Change in 2005-06: +19%
Growth rank: 11
Total population: 58,147,733
Total $100 million+ households: 530 (rank: 5)
Change in 2005-06: +18%
Growth rank: 12
No. 7: France
Total millionaire households: 265,000
Change in 2005-06: +24%
Growth rank: 7
Total population: 63,713,926
Total $100 million+ households: 260 (rank: 9)
Change in 2005-06: +19%
Growth rank: 9
No. 8: Taiwan
Total millionaire households: 220,000
Change in 2005-06: +13%
Growth rank: 12
Total population: 22,858,872
Total $100 million+ households: <140
Change in 2005-06: NA
No. 9: Switzerland
Total millionaire households: 205,000
Change in 2005-06: +25%
Growth rank: 6
Total population: 7,554,661
Total $100 million+ households: 300 (rank: 8)
Change in 2005-06: +20%
Growth rank: 7
No. 10: Brazil
Total millionaire households: 190,000
Change in 2005-06: +30.4%
Growth rank: 4
Total population: 190,010,647
Total $100 million+ households: 210 (rank: 10)
Change in 2005-06: +27%
Growth rank: 2
No. 11: Netherlands
Total millionaire households: 145,000
Change in 2005-06: +27%
Growth rank: 5
Total population: 16,570,613
Total $100 million+ households: 200 (rank: 11)
Change in 2005-06: 22%
Growth rank: 6
No. 12: Belgium
Total millionaire households: 135,000
Change in 2005-06: +23.6%
Growth rank: 8
Total population: 10,392,226
Total $100 million+ households: <140
Change in 2005-06: NA
No. 13: Australia
Total millionaire households: 135,000
Change in 2005-06: +22%
Growth rank: 9
Total population: 20,434,176
Total $100 million+ households: 150 (rank: 14)
Change in 2005-06: +20%
Growth rank: 8
No. 14: Spain
Total millionaire households: 125,000
Change in 2005-06: +32%
Growth rank: 2
Total population: 40,448,191
Total $100 million+ households: 330 (rank: 7)
Change in 2005-06: +24%
Growth rank: 5
No. 15: Canada
Total millionaire households: 110,000
Change in 2005-06: +8%
Growth rank: 14
Total population: 33,390,141
Total $100 million+ households: <140
Change in 2005-06: NA
Countries with the Most Millionaire Households - BusinessWeek