Peter Stokes, from the Office for National Statistics, says changing numbers of Welsh speakers in different parts of the country can partly be explained by migration within Wales.
- 93% of people in Wales were in the 'White: British / Welsh / Scottish / Northern Irish / British' ethnic group
- 97% of people in Blaenau Gwent and Caerphilly were in that 'White...British' ethnic group - the highest local authorities in Wales
- 80% of people in Cardiff were in that 'White...British' ethnic group - the lowest local authority in Wales
- 32% of people in Wales said they had 'no religion' - a higher proportion than any English region
- The proportion of people in Wales who said they were 'Christian' has decreased by 14% since 2001
The census figures show Wales compares badly with England in terms of people's healthiness.
- 8 of the top 10 local authorities with the highest proportion of residents who said they are in 'very bad health' are in Wales
- 78% of people in Wales described themselves as in 'good or very good health' - compared to 81% in England
- 23% of people in Wales had an activity-limiting long-term illness - compared to 18% in England
The number of people in Wales who can speak, read and write in the Welsh language has fallen over the last ten years. It dropped by 27,000, according to census figures released this morning.
- In 2001 - 458,000 aged 3 and over could speak, read and write Welsh
- In 2011 - 431,000 aged 3 and over could speak, read and write Welsh
According to the 2011 figures:
- 30% of Welsh speakers are under the age of 16
- 80% of people aged 45 to 49 said they had 'no skills in Welsh'
Today's census figures will focus on international migration, ethnic groups and religion - and the Welsh language.
Some parents like Rhian Cecil hope it'll lead to more Welsh medium and bilingual schools over the next ten years.
"It's really important for us as Welsh speakers to be stood up and counted".
"Hopefully all the figures can help local councils create more provision".
Key information about Welsh life over the past decade will be released today from the 2011 Census.
Interesting areas could include Welsh language and national identity, ethnicity, religion, migration and health.
The first release of 2011 Census data in July provided household and population estimates - by age and sex - for Wales and its local authorities.
It revealed that Wales' population now exceeds three million - an increase of five per cent in the past decade.
The latest figures will be published by the Office for National Statistics at 9.30am.