c# - LayoutPanel のパーセンテージ、実際にはどういう意味ですか?

Question

私はレイアウトパネルを20行に分割し、すべて同じサイズで均等に配置しています。20 行 @ 5% = 100% ですが、最後の行は他のすべての行の約 2 倍の大きさです。なぜこうなった？

   // LayoutPanel1
    // 
    this.LayoutPanel1.ColumnCount = 1;
    this.LayoutPanel1.ColumnStyles.Add(new System.Windows.Forms.ColumnStyle(System.Windows.Forms.SizeType.Percent, 100F));
    this.LayoutPanel1.Dock = System.Windows.Forms.DockStyle.Fill;
    this.LayoutPanel1.Location = new System.Drawing.Point(4, 4);
    this.LayoutPanel1.Margin = new System.Windows.Forms.Padding(4);
    this.LayoutPanel1.Name = "LayoutPanel1";
    this.LayoutPanel1.RowCount = 20;
    this.LayoutPanel1.RowStyles.Add(new System.Windows.Forms.RowStyle(System.Windows.Forms.SizeType.Percent, 5F));
    this.LayoutPanel1.RowStyles.Add(new System.Windows.Forms.RowStyle(System.Windows.Forms.SizeType.Percent, 5F));
    this.LayoutPanel1.RowStyles.Add(new System.Windows.Forms.RowStyle(System.Windows.Forms.SizeType.Percent, 5F));
    this.LayoutPanel1.RowStyles.Add(new System.Windows.Forms.RowStyle(System.Windows.Forms.SizeType.Percent, 5F));
    this.LayoutPanel1.RowStyles.Add(new System.Windows.Forms.RowStyle(System.Windows.Forms.SizeType.Percent, 5F));
    this.LayoutPanel1.RowStyles.Add(new System.Windows.Forms.RowStyle(System.Windows.Forms.SizeType.Percent, 5F));
    this.LayoutPanel1.RowStyles.Add(new System.Windows.Forms.RowStyle(System.Windows.Forms.SizeType.Percent, 5F));
    this.LayoutPanel1.RowStyles.Add(new System.Windows.Forms.RowStyle(System.Windows.Forms.SizeType.Percent, 5F));
    this.LayoutPanel1.RowStyles.Add(new System.Windows.Forms.RowStyle(System.Windows.Forms.SizeType.Percent, 5F));
    this.LayoutPanel1.RowStyles.Add(new System.Windows.Forms.RowStyle(System.Windows.Forms.SizeType.Percent, 5F));
    this.LayoutPanel1.RowStyles.Add(new System.Windows.Forms.RowStyle(System.Windows.Forms.SizeType.Percent, 5F));
    this.LayoutPanel1.RowStyles.Add(new System.Windows.Forms.RowStyle(System.Windows.Forms.SizeType.Percent, 5F));
    this.LayoutPanel1.RowStyles.Add(new System.Windows.Forms.RowStyle(System.Windows.Forms.SizeType.Percent, 5F));
    this.LayoutPanel1.RowStyles.Add(new System.Windows.Forms.RowStyle(System.Windows.Forms.SizeType.Percent, 5F));
    this.LayoutPanel1.RowStyles.Add(new System.Windows.Forms.RowStyle(System.Windows.Forms.SizeType.Percent, 5F));
    this.LayoutPanel1.RowStyles.Add(new System.Windows.Forms.RowStyle(System.Windows.Forms.SizeType.Percent, 5F));
    this.LayoutPanel1.RowStyles.Add(new System.Windows.Forms.RowStyle(System.Windows.Forms.SizeType.Percent, 5F));
    this.LayoutPanel1.RowStyles.Add(new System.Windows.Forms.RowStyle(System.Windows.Forms.SizeType.Percent, 5F));
    this.LayoutPanel1.RowStyles.Add(new System.Windows.Forms.RowStyle(System.Windows.Forms.SizeType.Percent, 5F));
    this.LayoutPanel1.RowStyles.Add(new System.Windows.Forms.RowStyle(System.Windows.Forms.SizeType.Percent, 5F));
    this.LayoutPanel1.Size = new System.Drawing.Size(150, 433);
    this.LayoutPanel1.TabIndex = 4;