Labeled [Histogram[{data},{Width},"Probability",LabelingFunction->Above,ImageSize->{820,530},PlotRange->All],{Rotate["relative",90 Degree],nameAxisX},{Left,Bottom}]

(* Generate some data from a beta distribution *)
data = RandomVariate[BetaDistribution[10, 0.5], 100];
(* Add some 1's *)
data = Flatten[{data, {1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1}}];

(* Resulting histogram *)
Labeled[Histogram[data, {0, 1.1, 0.1}, "Probability",
  LabelingFunction -> Above, ImageSize -> {820, 530},
  PlotRange -> All],
 {Rotate["relative", 90 Degree], "X"}, {Left, Bottom}]

Labeled[Histogram[Map[Min[#, 0.999] &, data], {0, 1, 0.1},
  "Probability",
  LabelingFunction -> Above, ImageSize -> {820, 530},
  PlotRange -> All],
 {Rotate["relative", 90 Degree], "X"}, {Left, Bottom}]

(* Generate some data from a beta distribution *)
data = RandomVariate[BetaDistribution[10, 0.5], 100];
(* Add some 1's *)
data = Flatten[{data, {1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1}}];

Width = Join[Table[i, {i, 0, 0.9, 0.1}], {1.0001}];

Labeled[Histogram[{data}, {Width}, "Probability",
  LabelingFunction -> Above, ImageSize -> {820, 530},
  PlotRange -> All], {Rotate["relative", 90 Degree],
  nameAxisX}, {Left, Bottom}]