Five billion people – or around two-thirds of the global population – are now connected on a mobile phone subscription, and that number is expected to continue growing through the end of the decade.

The milestone was announced on Tuesday by GSMA Intelligence, the research arm of wireless industry trade organization GSMA.

As of Tuesday morning, GSMA Intelligence’s mobile tracker calculated there were just over 5,006,489,000 individuals with mobile connections. It’s important to note that this figure is specifically counting unique subscribers rather than mobile connections. The latter figure is higher – standing at around 7.7 billion, excluding M2M connections – since a “unique subscriber” as defined by GSMA can have multiple connections or SIM cards.

GSMA Director General Mats Granryd in a statement called the figure a “tremendous achievement for an industry that is only a few decades old,” and said it was a reflection of “the many billions of dollars that mobile operators have invested in networks, services, and spectrum over many years.”

GSMA indicated more than half (55 percent) of global subscribers are in the Asia Pacific region, while Europe, Latin America, and Sub-Saharan Africa each account for around 9 percent of unique subscribers. North America is farther down the list with around 6 percent of the global subscriber base. China alone accounted for more than 1 billion, while India contributed a substantial 730 million. That latter figure was significantly more than the whole of Europe (465 million) and even topped the combined total for North America and Sub-Saharan Africa (which tallied to 728 million).

Though penetration is high in some regions – coming in at 86 percent in Europe and 80 percent in North America – GSMA Intelligence said there’s still room for significant growth.

GSMA said it took four years to grow from four billion subscribers to the current five billion, and is forecasting similar growth through the end of the decade. By 2020, the group said it expects nearly three-quarters of the world’s population – or around 5.7 billion people – to have a mobile subscription.

The additional subscribers are mainly expected to come from rural, low-income populations in underpenetrated markets like India. That country currently has penetration of around 54 percent, but is the subject of intense industry focus from companies like Apple. India is expected to account for the largest share of growth over the forecast period, responsible for around 30 percent of new unique subscribers by 2020.

A timeline of subscriber growth

According to GSMA figures, the number of unique global mobile subscribers first passed the one billion mark in 2003. Here’s a visual of how things progressed from there:

A GSMA infographic commemorating the 5 billion subscriber milestone can be found here.