Fall back to just using circle elements for markers in line charts
Fall back to just using circle elements for markers in line charts

Safari/Illustrator support for marker-mid is poor

aaldaber/owid-grapher,owid/owid-grapher,OurWorldInData/our-world-in-data-grapher,OurWorldInData/owid-grapher,OurWorldInData/owid-grapher,aaldaber/owid-grapher,owid/owid-grapher,owid/owid-grapher,aaldaber/owid-grapher,aaldaber/owid-grapher,owid/owid-grapher,OurWorldInData/our-world-in-data-grapher,OurWorldInData/our-world-in-data-grapher,aaldaber/owid-grapher,OurWorldInData/our-world-in-data-grapher,OurWorldInData/owid-grapher,owid/owid-grapher,OurWorldInData/owid-grapher,OurWorldInData/owid-grapher