title: How to make a clear date display on the axis (Altair)?
body: <p>My code</p>
  <pre><code>total_cases_graph = alt.Chart(subset_data).transform_filter(
      alt.datum.confirmed &gt; 0
  ).mark_line().encode(
      x=alt.X('date:T', type='nominal', title='Date'),
      y=alt.Y('sum(confirmed):Q',  title='Confirmed cases'),
      color='region_name',
      tooltip='sum(confirmed)',
  ).properties(
      width=1000,
      height=500
  ).configure_axis(
      labelFontSize=17,
      titleFontSize=20
  )
  </code></pre>
  <p>Now it is displayed like this</p>
  <p><a href="https://i.stack.imgur.com/GPvpW.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/GPvpW.png" alt="enter image description here" /></a></p>
  <p>I would like the dates to be less frequent, i.e. some dates were displayed at intervals</p>