Unofficial statistics suggest Google+ memberships have increased by over 30% since opening their doors last Wednesday, with the number of registered users at an estimated 44 million.

Statistician Paul Allen, claims his counting model -which uses a long list of surnames to count members- is a system that keeps pace with Google's own figures for the social network's activity.

He said: "In the past couple of days, since Google opened its doors to the general public over age 18, the growth rate has skyrocketed to rates we only saw during the first week of its 'field test' - back when it had a small number of users to begin with, the growth rates were of course much higher."

Now that Google have dropped the invite only system, Facebook may have a lot to lose in light of the largely unpopular changes Zuckerberg and his team have implemented.

Google have been less than willing to give out any official figures, despite there being plenty of interest in how Google+ stacks up against the growth of Facebook and Twitter. Let's remember, it has been in operation since late July, but growth in the past few days has equalled that of the growth in the earliest stages of the closed beta.

Since these figures hit the mainstream, Christian Oestlien the group product manager for social advertising at Google has openly spoke about how business profiles on Google+ are fast approaching.

The only official business accounts on the social networking site belong to Ford and General Motors and are predominantly for beta testing purposes.

Back in July, MTV and mashable were forced to close their accounts after Google told business users they could not set up accounts until it was ready. Now, dozens of big name brands such as Burger King and Starbucks have set up accounts.