Birth-year cohorts

This shows the number of active swimmers by birth year and age — the whole competing youth pool, not just those who reached a championship. A weak year-class (e.g. born 2011) shows up as a thin row years before it reaches the championships. Read a column downward (same age, different cohorts): a pale cell is a small cohort. "Strength" compares each cohort to the median of its age.

Born	9v	10v	11v	12v	13v	14v	15v	16v	17v	18v	Strength
Rollo
IKM
SM / NSM										›
2007	313	549	665	687	597	486	425	338	245	185	-3%
2008	336	549	720	664	610	564	461	371	294	203*	+4%
2009	315	533	621	671	641	562	449	368	268*		+1%
2010	337	482	663	726	678	600	493	380*			+6%
2011	236	444	569	626	579	496	380*				-11%
2012	226	446	584	636	584	498*					-11%
2013	253	474	636	669	601*						-6%
2014	266	488	587	538*							-8%
2015	339	519	498*								+7%
2016	349	363*									+11%

Born	9v	10v	11v	12v	13v	14v	15v	16v	17v	18v	Strength
Rollo
IKM
SM / NSM										›
2007	115	229	291	308	287	240	201	167	112	95	-1%
2008	109	220	310	298	272	250	200	161	141	98*	+0%
2009	129	222	270	276	281	238	189	159	129*		-1%
2010	144	214	284	315	291	257	214	180*			+6%
2011	97	172	228	246	220	193	154*				-19%
2012	83	182	258	272	245	209*					-15%
2013	114	231	288	299	269*						+1%
2014	98	196	252	224*							-12%
2015	134	220	211*								+8%
2016	155	156*									+35%

Born	9v	10v	11v	12v	13v	14v	15v	16v	17v	18v	Strength
Rollo
IKM
SM / NSM										›
2007	198	320	374	379	310	246	224	171	133	90	-6%
2008	227	329	410	366	338	314	261	210	153	105*	+4%
2009	186	311	351	395	360	324	260	209	139*		+1%
2010	193	268	379	411	387	343	279	200*			+5%
2011	139	272	341	380	359	303	226*				-7%
2012	143	264	326	364	339	289*					-10%
2013	139	243	348	370	332*						-12%
2014	168	292	335	314*							-6%
2015	205	299	287*								+4%
2016	194	207*									+0%

RolloIKMSM / NSM pale = uncommon age (SM/NSM has no lower limit) age 13 swims both Rollo and IKM; SM/NSM is also open to adults (19+)

Cell = active swimmers; colour = size relative to the strongest cohort at that age (per view). * = the current year (2026) is still in progress. Strength compares to the same-sex age median.

Using this for planning

A weak cohort (a negative strength) means that birth year will bring fewer swimmers to the championships a few years out — the forecast can't invent them, so it takes action now (recruitment, club work, retention). A strong young cohort signals future growth. Right now 2011 and 2012 sit clearly below the median, while 2015–2016 look strong — so the pipeline is recovering behind the dip. Switch the view (Boys/Girls): the 2011/2012 weakness is mostly boys (2011 boys ~−19 % vs girls ~−7 %); the girls' own soft spot is 2013.