Contrasting Bogaert's 1% figure, a study by Aicken et al., published in 2013, suggests that, based on Natsal-2 data from 2000-2001, the prevalence of asexuality in Britain is only 0.4% for the age range 16–44. This percentage indicates a decrease from the 0.9% figure determined from the Natsal-1 data collected on the same age-range a decade earlier. A 2015 analysis by Bogaert also found a similar decline between the Natsal-1 and Natsal-2 data. Aicken, Mercer, and Cassell found some evidence of ethnic differences among respondents who had not experienced sexual attraction; both men and women of Indian and Pakistani origin had a higher likelihood of reporting a lack of sexual attraction.