This example visualizes health survey data across time periods using a series of overlapping, semi-transparent rectangles. The bars are positioned along a time axis from the start to the end date of each survey, with their height reflecting the reported percentage value. A red line connects the midpoints of these intervals to highlight the trend over the years. The visualization is rendered as an SVG using React and D3.js v6, specifically employing `d3.scaleTime`, `d3.scaleLinear`, `d3.line`, and JSON data loading via `d3.json`.