There are an estimated 9 million IDNs (as of December 2018).
Between December 2017-2018 the growth rate of IDNs was 20%. This compares with -14% between 2016-2017 and 28% growth in 2015-2016.
After discounting the effect of .cn and .中国, the underlying IDN growth rate between 2017-2018 is 5.5%,
A note about IDNs under .cn and .中国, China (2017-2018)
A major driver in the increase of IDN numbers through 2018 was an update in the registration figures for .中国 (the top level IDN ccTLD for China). It has been challenging to obtain updated figures for China’s IDN ccTLDs since 2017. In line with industry practice (eg Verisign’s Domain Name Industry Brief), where updated figures for a TLD are not available we have provided estimates based on the last reported figures.