Visualizing counts in time series panel

I have a postgres database, with a time stamp field. Each row in the table is one transaction. We have thousands of transactions per second. I have gotten close with the x axis showing 1 hour grouping. I now want to have the y axis show how many transactions are in the hour group.

SELECT
$__timeGroup(attachtime, ‘1h’),
count(transid) as number
FROM rogerswork Where $__timeFilter(attachtime)
GROUP BY 1
ORDER BY $__timeGroup(attachtime, 1h);