There are an estimated 70 million people with Irish heritage living in the world today. Those born in Ireland, to Irish parents, or to grandparents who held Irish citizenship, are eligible to officially mark their pride in their heritage by applying for citizenship. 

But what about all the millions of people whose Irish ancestry dates back farther than two generations? 

In 2011, the Irish government launched the Certificate of Irish Heritage program, which offers people of Irish descent who are not eligible to apply for citizenship a way of formally marking their Irishness. 

It costs $45 (€40) for an unframed certificate; $133 (€120) for a framed one.

Since the launch of the certificates, which are handled by Kerry-based company Fexco, they've been gifted to celebrities ranging from President Obama to Tom Cruise to author Denis Lehane. These are known as "presentation certificates" – they are not applied for, but gifted by the Irish government. 

The 'paid for' certificates, however, haven't turned out to be quite as popular. 

Since 2011, the Irish Times reports, only 3,223 certificates have been issued, and 298 of these have been presentation certificates.

That means that fewer than 3,000 people out of the 70 million-strong Irish diaspora have paid to commemorate their Irish heritage. 

1,042 people applied for the certificate during the first year of the initiative, but that rate has since dwindled, with only 194 issued to date this year, 15 of which were presentation certificates. 

An announcement on the future of the scheme will be made in the coming weeks, the Irish Times reported.