Getting your business to $1 million in sales is hard enough, and for women, it's even tougher than it is for men. About 6.2 percent of firms owned by men reach the $1 million mark, but only 1.7 percent of companies owned by women reach that same size. So a man starting and running a business is about 3.5 times more likely to reach $1 million in revenues than a woman is.

But according to new data from the U.S. Bureau of Census, crunched by the U.S. Women's Chamber of Commerce, there are a few industries where women's odds of excelling are quite a bit better than the average, and in one standout industry, even better than those of men. A recent USWCC report lists various industries and the percentage of sales and companies in each that can be attributed to women.

By this analysis, the best industry for female entrepreneurs is clearly transportation and warehousing, where women own 15.2 percent of the companies but bring in 21.2 percent of sales. That's in contrast to the overall figures, which include all types of businesses, and show that women own 35.8 percent of companies but bring in only 4.2 percent of sales.

In construction, women-owned firms make up about nine percent of the industry and bring in six percent of the revenues. That might not sound great, but it qualifies construction as the second-best economic sector for women. Agriculture, forestry, and fishing comes next, with women owning 14.5 percent of businesses and bringing in 7.2 percent of sales.

The Census category of "other," or, in official-speak, "industries not classified" also performs relatively well for women, with the 37.9 percent of firms that are owned by women bringing in 24 percent of revenues. Maybe, for women entrepreneurs, the secret to success lies in doing something the Dept. of Census just can't quite figure out.

The big picture

Even though women seem to have relatively good odds in transportation and warehousing and in construction, the broader picture is not nearly so positive for women. In fact, according to the USWCC, that million-dollar benchmark became marginally harder for women to reach over the past five years, but a tiny bit more attainable for everyone else. On average, between 2007 and 2012, the amount of receipts brought in by women-owned businesses slid by $9,835.

In that same time period, other demographic groups saw their fortunes improve. The revenues of companies owned by men gained $27,768, and those of companies that were equally-owned by men and women (most often, husband-and-wife teams) had an average increase in revenues of $161,972.

A $9,835 decrease in the average revenues brought in by women, while small, is more important than it appears. First, of course, it's lousy that women's sales fell while men's were going up. And on average, given that a women-owned firm brings in only $141,000 a year, a $9,835 drop in revenues is significant.

The USWCC points to several possible reasons for this discrepancy. Access to capital is a huge factor, and the report points out that SBA loans, in particular, are more likely to go to male-owned businesses. The report asks that contracting officials be more diligent about opening the door to women-owned companies, and that the Small Business Administration makes sure the resources of its Small Business Development Centers are equally available to women.