Corporate Australia's success in lifting the proportion of women on boards to nearly 30 per cent in three years is a sign that gender diversity quotas are unnecessary, the Australian Institute of Company Directors argues.

Despite an uptick in the number of S&P/ASX 200 companies with no female board members, women accounted for 29.7 per cent of all board seats at the end of last year, a record high and within a whisker of the 30 per cent goal established by the AICD in 2015.