1. Volume 382, Issue 9907, Pages 1781-1794 (November 2013)
Changes in sexual attitudes and lifestyles in Britain through the life course and over time: findings from the National Surveys of Sexual Attitudes and Lifestyles (Natsal) 
Dr Catherine H Mercer, PhD, Clare Tanton, PhD, Philip Prah, MSc, Bob Erens, MA, Pam Sonnenberg, PhD, Soazig Clifton, BSc, Wendy Macdowall, MSc, Ruth Lewis, PhD, Nigel Field, MBPhD, Jessica Datta, MSc, Andrew J Copas, PhD, Andrew Phelps, BA, Prof Kaye Wellings, FRCOG, Prof Anne M Johnson, MD 
The Lancet 
Volume 382, Issue 9907, Pages (November 2013)
DOI: /S (13)
Copyright © 2013 Mercer et al. Open Access article distributed under the terms of CC BY Terms and Conditions

2. Figure 1
Association between key social determinants and (A) sexual behaviours and (B) attitudes in Natsal-3 participants aged 16–74 years, by sex
Horizontal bars indicate 95% CIs. NS-SEC excludes people who are long-term unemployed and full-time students. Oral sex is defined as mouth on a partner's genital area.21 Anal sex is defined as a man's penis in a partner's anus.21 QIMD=Quintile of Index of Multiple Deprivation.29 NS-SEC=National Statistics Socio-Economic Classification.28 *Not defined when asked in interview. †Participants aged ≥17 years.
The Lancet  , DOI: ( /S (13) )
Copyright © 2013 Mercer et al. Open Access article distributed under the terms of CC BY Terms and Conditions

3. Figure 2
Participants from Natsal-1, Natsal-2, and Natsal-3 reporting heterosexual sexual practices at any point, by sex and 10-year birth cohort
Each line connects values for the same birth cohort at different ages. Data for the 45–54 years age group missing for 1946–55 birth cohort, because only individuals aged 16–44 years were included in Natsal-2. Vaginal sex is defined as a man's penis in a woman's vagina.21 Oral sex is defined as mouth on a partner's genital area.21 Anal sex is defined as a man's penis in a woman's anus.21
The Lancet  , DOI: ( /S (13) )
Copyright © 2013 Mercer et al. Open Access article distributed under the terms of CC BY Terms and Conditions

4. Figure 3
Number of sexual partners of the opposite sex over the lifetime reported by participants in Natsal-1, Natsal-2, and Natsal-3, by sex and 10-year birth cohort
Each line connects values for the same birth cohort at different age groups. Data for the 45–54 years age group missing for 1946–55 birth cohort, because only individuals aged 16–44 years were included in Natsal-2.
The Lancet  , DOI: ( /S (13) )
Copyright © 2013 Mercer et al. Open Access article distributed under the terms of CC BY Terms and Conditions