colour markers by:

• year
• month
• year+month
• nothing

hide unselected markers
add marker outlines for better visibility

filter by dates (click to expand):

	01	02	03	04	05	06	07	08	09	10	11	12
2009	01	02	03	04	05	06	07	08	09	10	11	12
2010	01	02	03	04	05	06	07	08	09	10	11	12
2011	01	02	03	04	05	06	07	08	09	10	11	12
2013	01	02	03	04	05	06	07	08	09	10	11	12
2014	01	02	03	04	05	06	07	08	09	10	11	12
2015	01	02	03	04	05	06	07	08	09	10	11	12
2016	01	02	03	04	05	06	07	08	09	10	11	12
2017	01	02	03	04	05	06	07	08	09	10	11	12
2018	01	02	03	04	05	06	07	08	09	10	11	12
2019	01	02	03	04	05	06	07	08	09	10	11	12
2020	01	02	03	04	05	06	07	08	09	10	11	12
2021	01	02	03	04	05	06	07	08	09	10	11	12
2022	01	02	03	04	05	06	07	08	09	10	11	12

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