emissionsLinesPointGraph =
vl.data(combinedEmissions).encode(
vl.x().fieldT('TIME_PERIOD').axis({tickCount: 5}).title('Year'),
vl.detail().fieldN('POLLUTANT'),
vl.y().average('OBS_VALUE').title('Total Emissions (in Tonnes CO2 Equivalent)'),
vl.tooltip([{field: 'OBS_VALUE', type: "quantitative", title: 'Tonnes CO2E', formatType: 'iformat'}, {field: 'POLLUTANT', type: 'nominal', title: 'Pollutant'}]),
vl.color().fieldN('POLLUTANT'),
).layer(vl.mark({type:"point", filled: true}), vl.mark({type:"line"})).render();